A polybutylene terephthalate resin has excellent characteristics in injection moldability, mechanical properties, heat resistance, electrical properties, chemical resistance, and the like, and is widely used for an injection molded article in the fields of automobile components, machine components, electrical components, communication components, and the like. In addition, the polybutylene terephthalate resin is also excellent in mold transferability, therefore, is also used as a lamp member to be applied to an extension of an automobile that requires particularly favorable appearance.
However, it is known that when the polybutylene terephthalate resin is continuously molded, various kinds of gases (hereinafter, also referred to as “outgases”) are generated during molding, and further, an oligomer of polybutylene terephthalate, and the like adhere to a mold, remain on the mold, and become residues on mold. The residues on mold may impair the appearance of the molded article. Therefore, in order to constitute a component constituting a lamp for an automobile, which is required to have high brightness appearance (smoothness) and uniform reflectivity, etc., other lighting fixtures, or the like, a light-reflector component provided with a light reflection layer on a surface, or the like, in a case where a conventional polybutylene terephthalate resin is used, it is required to frequently clean the mold during continuous molding. In order to clean the mold, the production has to be suspended temporarily, therefore, the productivity is adversely influenced. According to this, a polybutylene terephthalate resin capable of suppressing the residues on mold has been demanded.
In addition, there may be a case where a product becomes high in temperature depending on the shape and specification of a lamp member, and a resin having high heat resistance is required in many cases.